Acronym for "fuck me or fuck off". An attitude in which if a person is sexually attracted to someone else, they either want to be dating/having sex with them or not associate with them at all, because just being friends isn't good enough.
1. "I'm not doing that friendzone shit, Modwina. fmofo"
2. "So I told Gretchen I don't feel like dating so now she's giving me the cold shoulder. She's such an fmofo."
Retard: You are one silly mofo.
Cool Guy: Oh no you did not...
Retard: Yes, I did. My mommy loves me and she said so too.
Cool Guy: SHUT UP, you fomofo!